1. We can find underground railways in many countries.
    我们可以在许多国家中发现地下铁路.

2. These men work underground for 6 hours at a time , mining for coal.
    这些人在地下工作一次挖煤6小时。

3. They stayed underground for twenty minutes and waited for the siren to sound again.
    他们在地下呆了二十分钟,等候警报器再一次响起.

4. This immense chasm has been formed by an underground stream which has tunnelled a course through a flaw in the rocks.
    这个深邃的洞穴是由一条地下暗泉冲刷岩石中的缝隙并使之慢慢变大而形成的。

5. He eluded capture for weeks by hiding underground.
    他为免被捕躲藏了几个星期.

6. Suddenly they came to a waterfall which droped into an underground lake at the bottom of the cave.
    他们突然遇见一条瀑布，它直泻入洞底的地下湖里。

7. Suddenly they came to a waterfall which dropped into an underground lake at the bottom of the cave.
    突然，他们来到一道瀑布前，那瀑布奔泻而下，注入洞底一处地下湖里。

8. Upon leaving Paris, trains will whistle along at an approximate speed of 186 miles per hour until they go underground, but will creep along as slow as 50 miles per hour behind local trains the last 68 miles to London.
    火车离开巴黎，呼啸着以大约186英里的时速驶入地下，行至距伦敦68英里处的时候，却只能跟在当地的火车后面，以每小时50英里的速度慢慢爬行。